Analog to digital Video conversion???

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fireball003

Joined: 28 Oct 2005
Posts: 194
Helped: 5

21 Apr 2006 15:35 Analog to digital Video conversion???

What stuffs do I need for the simplest and the easiest analog to digital video conversion system?

Can I do that using microcontroller such as LPC2148 what has both ADC and DAC built in? What is the limitation (if there any)?

Please upload or send me link of any related book or paper or tutorial and schematic.

Thanks a lot.

Buriedcode

Joined: 06 May 2004
Posts: 327
Helped: 34
Location: London

21 Apr 2006 15:46 Re: Analog to digital Video conversion???

hello,

Quote:

Can I do that using microcontroller such as LPC2148 what has both ADC and DAC built in? What is the limitation (if there any)?

As far as I'm aware, composite video has a pretty impressive bandwidth! Around 5-6Mhz. For an ADC, you would have to sample at least double this frequency, so 10-12Mhz (shannons theorem?). The anti aliasing filter would need a bit of room as well, meaning, you'd probably better sampling at 15-16Mhz.

I don't know the LPC2148 (is it an ARM7?) but I very much doubt it has an ADC capable of that. However, that doesn't mean the micro can't do something. You can get ADC's specifically designed for sampling video, and some include a filter, which is handy because they're a bitch to design.

Saying that, there 'may' be an IC about that does exactly what you want....with an ADC and all the conversion circuitry to convert analogue composite video to digital. Although, you didn't specify what you mean by 'digital'? Do you mean simply sampling the video signal? Or do you want it to be encoded into a MPEG stream?

Hope this helps in some way. Ps, Google has some stuff about digitizing video.

BuriedCode.

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fireball003

Joined: 28 Oct 2005
Posts: 194
Helped: 5

21 Apr 2006 20:07 Analog to digital Video conversion???

I found nothing specific on this topic searching by google.

# What stuffs do I need then?
# How would I convert video then?
# What's the difference between software codec and hardware codec? Can an ARM7TDMI-S handle the data flow using software codec?
# Please give me link of this type of project so that I can learn from those. Or any schematic.

Would anyone plz tell me in detail.

Thanks.

Buriedcode

Joined: 06 May 2004
Posts: 327
Helped: 34
Location: London

21 Apr 2006 20:45 Re: Analog to digital Video conversion???

Hi agian,

Quote:

I can't give you any detail until I have more information. Also, video isn't really my thing :/ You speak of 'codecs', so I assume you want to convert the video to a digital format such as MPEG, or some form of digital video stream. note: 'digitizing' simply means, sampling the analogue signal, it doesn't specify AT ALL what you want to do with this information. For example, if I 'digitize' and audio signal, that doesn't give me an MP3 or a WAV. It simply gives me a collection of numbers.

The 'front-end' for any digitizer just conditions, filters, and samples the signal....and because of the vast bandwidth...its pretty complicated. And THEN you must convert this to a known digital format (DVI?).

If you explain exactly what you wish to do Video -> Digitizer - > ??????
Then I will try and help you.

Got links?

http://www.ludd.luth.se/~d89-ahg/x_rapport/r78009.gif
http://www.wavetechservices.com/design.html
http://www.techmind.org/vd/mk1/vdescrpt.html
http://focus.ti.com/lit/ds/symlink/tvp7000.pdf
http://www1.cs.columbia.edu/~sedwards/digvid/schematics.pdf

good luck..

buriedcode